diff problems after bearing change

Did you fully seat the bearings on the diff?
You should use one of the old bearings to press the new ones on.

Did the caps go on the correct sides, with the correct carrier shims?
 
+1 on above. Explain HOW you set the pinion preload. Explain how the bearings were removed and the new one's installed. Did you take any measurements of the pinion depth before dis-assembly?

Is it possible it's not turning because the back-lash is zero (or negative)? If so, this could be because of the pinion depth or carrier shims.
 
  • Like
Reactions: trinity_gt
+1 on above. Explain HOW you set the pinion preload. Explain how the bearings were removed and the new one's installed. Did you take any measurements of the pinion depth before dis-assembly?

Is it possible it's not turning because the back-lash is zero (or negative)? If so, this could be because of the pinion depth or carrier shims.

Agreed, something is definitely not right in the setup.
 
Ok thanks wmburns. I checked the pinion and it was not set correctly. I bought the a few days ago so I didnt know how the gear was done or who did it. Evidentaly that is why the diff bearings went bad. Reset the pinion and now all is good in the mustang world. Car feels like it has 50 more horsepower now. Thanks
 
  • Like
Reactions: gearheadboy
I dunno sounds like something else was wrong ,like incorrect carrier bearing preload.
It seems to me that if it was a pinion depth issue you would be most likely to have issues with the inner and outer pinion bearing and not carrier bearings as your post seems to imply. JMHO